1. Field of the Invention
The present invention relates to a magnet switch for a starter of an internal combustion engine.
2. Related Art
In a starter having a conventional magnet switch, for example, the magnet switch disclosed in Japanese Utility Model Publication 01-24830, the magnet switch is disposed on the upper portion of a d.c. motor and is fixed by a screw. A fixed seat surface of a battery connecting terminal is located inside of the d.c. motor axial to its back end portion. The cap of the magnet switch is disposed having a stage between the fixed seat surface and a fixed seat surface of the d.c. motor input terminal. These fixed seat surfaces are caulked via a washer with the battery connecting terminal for the fixed seat surface and the d.c. motor input terminal for the fixed seat surface. This publication also discloses a structure which can install a battery cable at any place around the magnet switch as the fixed seat surface of the battery cable connecting terminal protrudes more than the fixed seat surface of the d.c. motor input terminal.
However, as for a starter having magnet switch as described above, especially a low torque speed reduction type starter employing a magnet as a field device for the d.c. motor, a battery cable is wired in the upper portion of d.c. motor because a fixed seat portion of the battery connecting terminal is located on the interior side of the back end portion of d.c. motor. In this state, when an electric current is applied to the battery cable, a magnetic field is produced. This magnetic field changes the magnetic flux of the magnet in the field device, thereby causing a phenomenon where the starter efficiency deteriorates to the same degree as the magnetic flux is changed. In addition, although such a starter can have the battery cable installed at any direction around the periphery of the battery connecting terminal, as a battery cable is disposed in the upper portion of a d.c. motor, when a vehicle vibrates, the battery cable scrapes the d.c. motor so that an insulating coating of the battery cable may peel off.